Microsoft paid billions for a license to Nokia's patents, but the company has made explicit that Nokia still owns the patents. The genius of this move is that it allows Microsoft to double down on its patent war with Android. Microsoft boasts that the majority of Android phones sold worldwide have already paid for a license to Microsoft patents. By 2011, patent licensing revenue exceeded Microsoft's revenue from Windows Phone.

Now, Nokia can go after Android phone makers for royalties - even ones that have already paid Microsoft.